a lot of times when a sympton of loosing volume after a period of time is given the suggestion is to replace the caps if there leaky. why if a cap is leaking would it take sometimes in order of 30 minutes to act up. if it is leaking it would fade out right away true?

:a lot of times when a sympton of loosing volume after a period of time is given the suggestion is to replace the caps if there leaky. why if a cap is leaking would it take sometimes in order of 30 minutes to act up. if it is leaking it would fade out right away true?

Not true. Leaking caps can cause a lot of different symptoms: squealing, loss of highs or lows, pops and crackling, fading etc--and this can come and go because the radio will heat up.

Hi Johnnysan and Carlos,
I have heard many problems caused by leaky capacitors. Classis is weak performance and depressed plate voltage levels all around the radio. Also heard is hum and static.
I wrote the article on paper wax capacitors for eBay. Here is the link to the revised version. http://www.avorex.com/PaperWax/Paperwax.htm

Best Regards,

Bill Grimm

Carlos

A leaky cap can cause a tube to run away with current.

If a grid cap is leaky a tube will have reduced or no grid bias. This causes it to draw excessive current. The tube can start operating but continues to draw more and more current until it no longer acts as an amplifier. It might take 15 minutes to get to this point.

Norn\m

:a lot of times when a sympton of loosing volume after a period of time is given the suggestion is to replace the caps if there leaky. why if a cap is leaking would it take sometimes in order of 30 minutes to act up. if it is leaking it would fade out right away true?

: Norm & Carlos,

Norm, I agree. I once had a leaky grid cap on a 6A7 pentagrid converter. The radio would turn on play fine for awhile, but as it warmed up, the volume would begin to diminish, and the set would eventually cut out altogether. During the process of turning it off after it had stop working, I could hear the broadcast again....just for a split second. Carlos, Norm has a good point. You may wish to gently check to see if any of the grid caps on your tubes wobble when you touch them. Although the filament inside made still be electrically connected, a separation of the cap from the tube could be a problem.

:Carlos
:
: A leaky cap can cause a tube to run away with current.
:
: If a grid cap is leaky a tube will have reduced or no grid bias. This causes it to draw excessive current. The tube can start operating but continues to draw more and more current until it no longer acts as an amplifier. It might take 15 minutes to get to this point.
:
:Norn\m
:
::a lot of times when a sympton of loosing volume after a period of time is given the suggestion is to replace the caps if there leaky. why if a cap is leaking would it take sometimes in order of 30 minutes to act up. if it is leaking it would fade out right away true?